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    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <script>
      // 倒三角
      var str = ''
      for (var i = 1; i <= 10; i++) {
        // for (var j = i; j <= 10; j++) {
        //     str = str + '★';
        // }
        for (var j = 10; j >= i; j--) {
          str = str + '★'
        }
        str = str + '\n'
      }
      console.log(str)
      // 正三角
      var str = ''
      for (var i = 1; i <= 10; i++) {
        for (var j = 1; j <= i; j++) {
          str = str + '★'
        }
        str = str + '\n'
      }
      console.log(str)
    </script>
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  <body></body>
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